China is "strongly concerned" about a case in which six Chinese nationals were charged by the United States with economic espionage, it said. Chinese Foreign Ministry spokesman Hong Lei made the remarks at a regular briefing, adding the country would work to safeguard the rights and interests of its nationals. The U.S government charged six Chinese nationals with economic espionage, saying they stole secrets from two companies that develop technology often used in military systems, the Department of Justice said.